Russian investigators have ended their probe into the death of Sergei Magnitsky, the lawyer who died in prison in 2009 after accusing Russian officials of large-scale embezzlement of tax money, saying he suffered no abuse while incarcerated.

Russia's Investigative Committee said Tuesday that it had closed its investigation into Magnitsky's death because it found no evidence he was subjected either to "special conditions" or to "physical abuse or torture" in prison. It said he died of cardiac failure.

Magnitsky, a lawyer who worked for Hermitage Capital Management, which was the largest Western investment firm operating in Russia, accused Russian law enforcement and tax officials of a scheme by which they fraudulently received refunds for taxes that Hermitage paid in Russia, totaling $230 million.

Magnitsky was subsequently arrested on charges of tax evasion. He died in prison at age 37, after being detained for nearly a year and saying he was denied medical attention.

In 2011, an investigation by then Russian President Dmitry Medvedev's human rights council found that Magnitsky, who had pancreatitis, had been "completely deprived" of medical care before his death. It added there was "reasonable suspicion" to believe Magnitsky's death was triggered by a beating.

A report by Hermitage Capital Management founder William Browder that year claimed Magnitsky died about an hour after being beaten by prison guards.

Magnitsky's case became a symbol of alleged prison abuse in modern Russian and led to a fresh dispute between Moscow and Washington.

The United States enacted the Magnitsky Act, imposing a visa ban and financial sanctions on Russian officials accused of human rights violations.

Russian President Vladimir Putin then quickly signed a law banning Americans from adopting Russian children.

Thursday's announcement that the probe into Magnitsky's death had been closed came less than 24 hours after prosecutors in the southwestern U.S. state of Texas said they would not charge a couple in the death of a three-year-old adopted boy from Russia.